Electric welding machine



Nova 29, 1932. e. A. LUTZ ELECTRIC WELDING MACHINE Filed Aug. 22, 1929 INVENTOR $60 /7. Z. @1222 ATTORNEY Patented Nov. 29, 1932 UNITED STATES PATENT OFFICE GEORGE A. LTITZ, 0F CRAN'FOBD, NEW JERSEY, ASSIGNOR TO AMERICAN CIRCULAR LOOK OOIPANY, IKCL'OF DOVER, DELAWARE, A CORPORATION OF DELAWARE HIECTBIC WELDTNG MACHINE Application filed August 22, 1929. SerialNo. 387,825.

In the art of electric welding, when a pair of adjacent annular terminal electrodes are used, the heat generated at the place of contact between the electrodes and the metal to be welded has the tendency to cause the operative ed es of the electrodes to soften and become in ured, the metal of one electrode at such edge tending to become burred or pressed toward the adjacent electrode, thereby shortening the space between the electrodes and rendering them inefficient.

The object of my invention is to prevent the expansion or distortion of the metal of the electrodes at their inner or contact edges.

I provide means to automatically prevent the metal at the edges of such electrodes from expanding laterally during use, and to, in effect, iron back said edges so that they w1ll retain their proper shape and spacing to maintain the electrodes in substantially their original condition, to assure the proper passage of the electric current between the electrodes at the welding oint as the electrodes rotate against the wor In the form of my invention illustrated I provide a transformer with spaced annular terminal electrodes to engage the metal to be welded, and at a suitable distance from said electrodes rotative rolls are mounted to engage the peripheries of the electrodes, which rolls have flanges to engage the edge portions and inner faces of the adjacent electrodes to keep a pressure against the said edges and faces and prevent them from becoming expanded or displaced toward one another, to retain the symmetry of the electrodes during use.

My invention also comprises novel details of improvement that will be more fully hereinafter set forth and then pointed out in the claims.

Reference is to be had to the accompanying drawing, wherein Fig. 1 is a plan view of a rotary transformer embodying my invention;

Fig. 2 is a partly broken side View of Fig. 1;

Fig. 3 is a section on line 3, 3 in Fig. 2;

Fig. 4 is an enlarged section on line 4, 4 in Fig. 2;

Fig. 5 is a detail of one of the pressing rolls, and

Fig. 6 is a detail of a modified roll.

Similar numerals indicate corresponding parts in the several views.

At 1' is illustrated a rotary electric transformer of a well known type, which may be substantially of the class set forth in Letters Patent No. 1,47 8,262, issued Dec. 18, 1923, to Snoddgrass and Hunter, although my improvements may be adapted for usein any desired machine having rotary terminal electrodes spaced apart. The secondary 2 of the transformer 1 shown is carried bythe rotary shaft 3 journaled in bearings in the transformer frame 4, said parts and the primary of the transformer being substantially as set forth in said patent, or as set forth in Letters Patent to me No. 1,594,891, issued August 3,

1926. At 5 and 6 are a pair of annular secondary term nal electrodes providing rotary contacts, which are spaced apart on a common axis and insulated from each other, as,

by insulation at 7 The electrodes may be secured together by screws, at 8, provided with suitable insulation in a manner set forth in said patents. The electrodes 5 and 6 are adapted to bear against the metal '9 to be welded at its seam 10. I have illustrated the metal or work 9 in the form of a tube or pipe, and at 11 is a guiding roller for the tube or pipe journaled upon a shaft 12 carried by the main frame. The peripheries of the electrodes and of the roller 11 are shown curved or grooved to substantially correspond to the the electrodes are usually made of copper or suitable alloy the heat generated at the welding point or place of contact and the pressure between the electrodes and the tube blank at the inner edges and faces at 5a and 6a of the electrodes (Fig- 4), tend to soften the electrodes and thereby to' cause them to spread or to expand toward one another, tending to reduce the efliciency of the weldin operation. To overcome the aforesaid di culty it has been proposed to apply a tool to the edges, at 5a and 6a, of the electrodes during welding to cut off the displaced metal of the said edges and displace adhering parts, but this has the disadvantage of'continually reducin the diameter of the electrodes at the inner e ges. I provide rolls or rollers, at 13 and 14, adapted to engage the electrodes 5 and 6, respectively, said rolls having a curved contour to properly engage the grooved or recessed peripheral portions 5' and-6 of the electrodes, (Fig. 4) Said rolls are provided with peripheral flanges 13 and 14 adapted to bear a ainst the inner surfaces of the electrodes wlth the edges 5a and 6a of the electrodes located at the point of junction between the curved surface of the corresponding roll and its flan e, (Fig. 4), so as to resist displacement o the metal of, the election Wlth respect to the electrodes, (Fig. 4).

The surfaces of the rolls 13 and 14 may be smooth, to conform to the surfaces 5' and 6' of the electrodes, or the rolls may have knurled surfaces at 14a, as illustrated in Fig.

,6, to facilitate rotation of the rolls in contact with the electrodes.

When the tube blank or work is being welded the electrodes rotate in contact therewith, and the rolls 13 and 14 are maintained in contact with the electrodes and are rotated thereby as the blank travels through the pass,

- the blank being moved in any well known way. The engagement of the flanges of the rolls with the inner surfaces and the edges 5a and 6a of the electrodes serves to keep said surfaces and edges smooth, and prevent them from expanding or swelling toward one 1. In an electric welding machine a pair of spaced annular terminal electrodes having a common axis and having peripheral grooves and inner flat surfaces, and means maintained in contact with the grooves and flat surfaces of said electrodes and bearing against said grooves and surfaces to prevent expanding of the electrodes toward each otherto resist reduction of spacing between the electrodes due to heat and pressure on the work during welding.

2. In an electric welding machine a pair of spaced annular terminal electrodes having a common axis, and rol -2s having flanges maintained in contact with the inner edge portions of the electrodes and the inner faces thereof preventing distortion of the electrodes at their inner edges to maintain a substantially uniform resistance at the welding point.

3. In an electric welding machine apair of spaced annular terminal electrodes having a common axis and having peripheral grooves and inner flat surfaces, and rolls rotativey maintained in contact with the electrodes. said rolls having flanges located in the space between the electrodes and in engagement with said inner surfaces of the electrodes adjacent to their inner edges to prevent expanding ofthe electrodes at the said edges to maintain a substantially fixed spacing between the electrodes, the rolls being in contact with the surfaces of the electrodesin said grooves.

4;. In an electric welding machine a pair of spaced annular terminal electrodes having. a common axis, and rolls rotatively maintained in contact with the electrodes, said. rolls having flanges located the space between the electrodes in engagement with the inner surfaces of the electrodes adjacent to their inner edges to prevent expanding of the knurled surfaces to engage the electrodes to facilitate rotation of the rolls in contact withthe electrodes.

GEORGE A, LUTZ.

another, or in the direction of the space between the electrodes, so as to maintain the original or symmetrical configuration of the electrodes,- and prevent short-circuiting by contact of the electrodes, as well as to pre-' vent reduction of the space between the-electrodes with consequent loss of welding efficiency. The contact of the rolls with the peripheral surfaces of the electrodes serves to keep them from expanding under the influence of the heat in the electrodes, by reason of the pressure of the flanges and the rolls against the electrodes.

Having now described my invention what I claim is: 

